Abrasive block or segment



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ATTORNEYS.

Patented Mar. 2l, 1950 UNITED STATES PATENT oFEicE ABRASIVE BLOCK OR SEGMENT Albert Shepard Titcomb, South Warren, R. I.

Application June 1, 1949, serial No. 96,476

`17 Claims. (Cl. 51-209) This invention relates to an abrasive grinding wheel which is composed of a plurality of spaced abrasive surfaces, and more particularly to the abrasive block or segment which is utilized for such a wheel. This application is a continuationin-part of my co-pending application Serial No. 679,807, issued July- 19, 1949, Patent Number 2,476,334, which claims more particularly the wheel as a whole, while this application is directed specifically to the segment or block per se which goes into such wheel.

Abrasive grinding wheels of the above character have heretofore been constructed of al grinding segment composed of abrasive material shaped like a hollow cylinder, known in the trade as an inverted cup. The sides of the cup are often made of segments each locking into the next segment or sometimes by segments with spaces in between with locking devices to hold the sides'of the cup to the upper base of the grinding wheel by means of what is known in the trade as the chuck. This wheel is intended for operating on a mounting at the bottom of a rotating vertical spindle on work fastened to a movable base (either rotary or reciprocative) and where the revolving segments are pressed downward against the work. It is also intended for operating on a mounting at one end of a horizontal spindle on work fastened to a reciprocating table so that the revolving segments are pressed against the work. When the wheel is applied to the work, chips of the work and also of the cutting wheel are formed by removal of the stock of each. This removed stock will load up or interfere with the efticient cutting action p ecient cutting wheel. It has been found that l throw the work off the magnetic chuck, generally used, sometimes with serious results.

One of the objects of this invention is to provide a block for an abrasive grinding wheel, which block will be of such shape that it will provide a more ecient and freer cutting wheel action than similar segmental block wheels have heretofore accomplished.

Another object of this invention is to provide a shape of abrasive block so'that chips willbe self-removed eiciently and thus prevent loading of the wheel.

Another object of this invention is to provide an abrasive block which will cause its leading edge to have an eicient plow action upon the chips which are formed to spread the chips out"- wardly and inwardly of the Wheel as the cutting surface of the block advances.

Another object of this invention is to provide an abrasive block which, when in a wheel, will run cool and free of loading and thus prevent heating and warping of the Work.

Another object of this invention is to provide an abrasive block which will be of such form that it may be utilized in a plurality of different di'- ameter wheels, thus enabling lower cost to manufacture through the standardization and also greater economy in cases where there is need of replacement through damage.

With these and other objects in view, the invention consists of certain novel features of construction, as will be more fully described and particularly pointed out in the appended claims.

In the accompanying drawings:

Figure l is a perspective view of an abrasive block formedin accordance with this invention;

Figure 2 is a plan view of several of the abrasive blocks arranged in the form which they will as'- sume in a grinding wheel utilizing abrasive blocks of this shape; i

Figure 3 is a diagrammatic view of the basic form of a segment or block having rather ideal plow-like properties when in action if the same were drawn in a straight line;

Figure 4 is a view similar to Figure 3, but illustrating the segment as being developed into an arcuate form or shape desirable for grinding l wheel purposes; i

Figure 5 is a plan view of a block illustrating a modied shape so far as Figure 4 is concerned, but showing diagrammatically by means of radius lines the shaping of the block such as is shown in Figure 3; y

Figure 6 is a diagrammatic view illustrating a further modication showing the arcuate lines .forming the edges of the block and their radius lineswheretruearcsgotomakeupthesegment formed:

Phare 'I is a atie view illustrating a segment formed from two arcs:

Figures 8, 9, 10, 11. and 12 are diagrammatic views each showing an inner edge having a single are, while the outer surface of the segment is formed arcuate each of different form by dliierentformstionsofthe surface;

Figures 13 to 18 and 18 are diagrammatic views illustrating segments each of modified form and showing the inner surfaces of the segments each different but formed from fiat and curved surfaces of varying form although generally of the same characteristics; and

Figure 17 illustrates a segment which is substantially one-half of the segment shown in Figure 1.

In proceeding with this invention, I have consia-usted an abrasive block or segment of an elongated shape which will have pointed ends. The leading pointed end will be so positioned in the wheel that the opposite flaring edges from the leading end will have a plow action upon the chips and debris removed by the preceding segment. These blocks are all of the same size and shape for standardization and for grinding wheels of different diameters, and I usually mount more upon a larger wheel than on a smaller wheel in order to provide the size of grinding wheel deaired. ILillie blocks may also be arranged in overlapping circular echelon relation so that a continuous cutting surface is provided on the work, thus preventing the opportunity for the stock being ground to rise, and at the same time providing necessary chip clearance between blocks or segments. The overlapping relation will be so spaced that the chips removed from the work may be thrown aside from the wheel by cenia'ifugal force as well as by physical displacement of the plow action referred to above. Coolant is usually delivered at a location just inwardly of the circular cutting annulus of the wheel and news to the work surface within this annulus. For greater detail concerning the wheel itself, reference is made to the above-mentioned copending application.

By the term;"arcua I mean a line which maybe shaped like the bow of a bow and arrow and formed of portions of several true arcs struck from ntcrs or a line which may be formed of fiat surfaces at obtuse angles to each other and polygonal in plan or a line made up of arcs and fiat surfaces generally in the form of the median line or either edge depicted in the various views.

Aline of less curvature means nearer a straight line and greater or sharper curvature would mean further from a straight line.

With reference to the drawings, Figure 1 shows a. perspective view of an abrasive block or segment il of a commercial form which is the subject of this invention. Four of such blocks are shown in Figure 2 in the arrangement which will occur when assembled as an abrasive wheel indicated by dot and dash lines 9|. In each case the leading end I2 of the block will be nearer the center of the wheel than 'the trailing end l! so as to arrange the blocks in a circular echelon relation with the leading end of one block usually overlapping the trailing end of the next block so that engagement with the work is continuous.

In Figure 3 I have illustrated at |00 a fundamental form of abrasive block which will have pointed ends i| formed by reducing the thickness from the extreme width along a substantial length. As most grindingwheels are formed in circular shape, the abrasive block which will be used will be of arcuate shape and will be developed from the fundamental form shown in Figure 3 by determination of the general curvature of the block desired which may be the median line or center line of the block |02 from which the shape is developed. Figure 4 designates such median line with the opposite edges layed oif on either side of the median line as equal dimensions along radii |02' from the center of the median line, or if this median line is not a true arc having a. center butvis rather arcuate in form, the layout will be along lines at right angles to the portion of the arcuate line at different points along its length. In Figure 4 the inside arcuate edge `of the block is shown to have a reverse curve |03 as it approaches the median line to form an acutely angled end.

A form which is found to be suitable is shown in Figure 5 where the median line |04 is formed on the are of a circle having a radius |05. while the inner and outeredges of the block are arcuate, the outer surface having a center arc from radius |06 with arcs from shorter radii at each end such es |01 joining the center arc to the median line at |08. The inner edge of the block is also arcuate having a center arc from radius |00 which is connected by straight lines such as `I I0 to the ends |08 which are on the median line. A perspective view of the block so formed is shown in Figure 1. In each case, however, acutely angled ends are provided.

In some cases, as shown in Figure 6, there may be a single inner'arc for the inner surface ci' the block which is designated ||2 and struck from the radius H3, while the median line may be an are ||4 having radius H5 with the outer surface i i6 arcuate and formed from arcs having radii lil and other radii H8 of shorter radius at the ends, thus forming acutely angled ends H9. `In some cases I may provide a segment formed of two arcs, as shown in Figure 7, there being an inner arc |20 formed on radii |2| and an outer arc |22 formed on radii |23, thus also providing acutely angled ends |24 but of a much thinner and more fragile character.

In Figure 8 I have shown an inner surface formed from a single arc |25, while the outer surface |26 is formed arcuate having arcs v|2`| at either end joined by a. flat portion |28 which may be raised as -at |28'. In Figure 9 I have shown the inner surface |29 formed from an arc of a single radius, while the outer surface |30 is formed from a plurality of flat surfaces I3| each in an obtuse angle to each other but generally conforming to the shape defined in Figure 6. In Figure 10 the same general arrangement. as shown in Figure 9, is provided, there being an arc of uniform radius |32, while the outer surface |33 is formed from a. plurality of flat surfaces |34 longer than the ilat surfaces |3| and each at an obtuse angle to the next one but all generally conforming to the shape of the arcuate surface H6 of Figure 6.

Modifications of the outer surface of the segment are shown asin Figure 11, there being a curved middle portion |35 joined by three flat surfaces |36, |31, and |38 to form the end portion of the block, while in Figure 12 the outer surface is composed of an arc |33 Joined by a single fiat surface |40 at either end of the block to connect with the inner surface of the block.

The inner surfacev of the block may a'lso be formed arcuate in several different forms and these are shown in Figures 13, 14,'15, and 16. In Figure 13 the inner surface is formed from a plurality of short flats |4| each at an obtuse angle to each other, while in Figure 14 there are longer fiat surfaces |42 connected by shorter fiat surfaces |48 each at an obtuse angle. In

Figure 15 three flat surfaces are provided, there being a middle flat surface IM and end fiat surfaces |45, while in Figure 16 two fiat surfaces |45 are provided meeting at the center |41.

The above blocks all provide practical schemes modified by an arcuate surface .intersecting said of forming blocks which may be'disposed in the circular relation which is shown in the wheel of Figure 2, it being merely necessary to utilize one of these many forms for many -wheels of different diameter which may be desired. The holders vfor the blocks or clamps wi'll, of course, be uniform and of a shape to cooperate with the particular shape of block desired. From a strength characteristic standpoint it is desirable to have the ends of thicker or heavier section in order that they may be stronger and the form which I have shown in Figures 1, '2, and 5 is found to be the more suitable in this regard rather than the more fragile section of Fig. 7. The many forms illustrated, however, indicate the. v-ariations which may be adopted and combinations of which come within the purview of this invention.

In Figure 17 I have shown va block 95 which is substantially one-half of the block shown in Figure 1, which in some cases it may be desirable to use.

I claim:

1. A bonded abrasive block shaped as a pseudo A hollow cylindrical segment, formed between two arcuate surfaces, said arcuate surfaces being permedian.

8. A bonded abrasive block as in claim 1 wherein said inner surface is modified at its acutely angled end through a merging of the interior-arcuate surface into an arcuate surface ofl reverse direction carried to said median.

9. A bonded abrasive block as in claim 1 wherein said opposite ends are symmetrical.

10. A bonded abrasive block shaped as a pseudo hollow cylindrical segment of symmetricai form comprising leading, center and trailing portions, sa-id center portion being formed between inner and outer arcuatesurfaces both perpendicular to an end surface, said leading and trailing portions being symmetrical and meeting in acutely angled sharp ends formed through modifications .of at least one of said inner and outer arcuate surfaces. y

11. A bonded abrasive block as in claim 10 wherein one of said arcuate surfaces merges into a flat plane carried to said end.

12. A bonded abrasive block as in claim 10 wherein said inner arcuate surface merges into a flat plane carried to the said end.

13. .A bonded abrasive -block as in claim 10 wherein one of said arcuate surfaces rrerges into an arc of shorter radius carried to said end.

14. A bonded abrasive block as in claim 10 wherein said exterior surface comprises a mid arc merging into an arc of shorter radius carried to said end.

pendicular to an end surface and substantially i equidistant throughout their course from an arcuate median, said inner and outer arcuate surfaces meeting at said median in an acutely angled sharp end.

2. A bonded abrasive block as in claim 1 wherein one of said arcuate surfaces comprises an arcuate surface merging into a fiat plane carried to the arcuate median.

3. A bonded abrasive block as in claim 1 wherein said inner surface comprises an arcuate surf-ace merging into a at plane carried to the arcuate median.

4. A bonded abrasive block as in claim 1 where-` in one of said surfaces comprises an arc merging into an arc of shorter radius intersecting said median.

5. A bonded abrasive block as in claim 1 wherein said exterior surface comprises a mid arc merging into an are of shorter radius intersecting said median.

6. A bonded abrasive block as in claim 1 wherein one of said surfaces comprises a flat surface modified by an arcuate surface intersecting said median.

7. A bonded -abrasive block as in claim l'wherein said exterior surface comprises a fiat surface 1 5. A bonded abrasive block as in claim 10 wherein said inner arcuate surface is modified at its acutely angled endthrough -a merging of the interior arcuate surface into an arcuate surface of reverse direction carried to said end.

16. A bonded abrasive block as in claim 10 wherein one of said surfaces comprises a flat sur' face modified by an arcuate surface carried to said end. v y

17. A bonded abrasive block as in claim 10 wherein saidexterior surface comprises a fiat surface modified by an arcuate surface carried to said end.

ALBERT SHEPARD TITCOMB.

REFERENCES CITED The following references are of record in the file of this patent: I

UNITED STATES PATENTS switzerland July 15, 1910 

